Glutathione peroxidase activity and reduced glutathione content in erythrocytes of patients with chronic renal failure

Oxidative stress in children with kidney disease

The aim of this work was to study the dynamics of oxidative stress in the blood and urine of children with kidney diseases: glomerulonephritis (GN), pyelonephritis (PN), renal failure (RF), and lower urinary tract infections (LUTI). The concentration of conjugated dienes is increased in blood: GN 4 times and RF up to 2 times; and extremely increased in urine: GN 12 times and RF 4 times. The concentration of thiobarbituric acid reactive substances in urine shows a similar trend: GN 7 times, PN 2 times, RF 1.5 times, and LUTI almost 3 times. Urine chemiluminescence is also increased: GN 5 times, PN and LUTI 3 times, and RF 6 times. Kidney disease leads to 2.5-fold inhibition of antioxidant catalase activity in blood and 10-fold in urine. Total antioxidant activity of urine is induced in all groups: GN 18 times, PN 2 times, RF 1.5 times, and almost 4 times in the LUTI group. Experimental data confirm that products of lipid peroxidation, intensity of chemiluminescence, and total and enzyme antioxidant capacity in combination with clinical parameters are a proper test for the dynamics of oxidative stress and markers of intoxication in children with inflammatory and immunological active parenchymal kidney disorders. These data could be helpful for the optimization of complex and effective antioxidant therapy of children with kidney disease.

Red cell lipid peroxidation and antioxidant system in haemodialysed patients: influence of recombinant human erythropoietin (r-HuEPO) treatment

In order to determine the role of correcting anaemia with r-HuEPO on susceptibility of red cell to lipid peroxidation, 15 patients on maintenance haemodialysis treated with r-HuEPO for at least one year (group I), 15 patients on maintenance haemodialysis without r-HuEPO (group II) and 30 persons as a control group (group III) were included in the study. We measured erythrocyte superoxide dismutase (e-SOD), erythrocyte catalase (e-CAT) activities, plasma malonyldialdehyde (p-MDA) and serum vitamin E levels in all patients. The healthy controls (group III) had significantly lower levels of p-MDA in comparison to those measured in haemodialysed patients (group I-II) (p < 0.0001). e-SOD activity in group III was significantly higher than in groups I and II, respectively (p < 0.0001 and p < 0.00001), and e-SOD activity was significantly lower in group II than in group I (p < 0.0001). e-CAT activity in group III was higher than in groups I and II, respectively (p < 0.0001 and p < 0.00001) and it was significantly lower in group II than in group I (p < 0.0001). Vitamin E concentration in group III was lower than in group I and group II, respectively (p < 0.0001 and p < 0.0001). But there is no difference between groups I and II. This study suggests that r-HuEPO therapy improves anaemia by decreasing lipid peroxidation and increasing antioxidant activity.

Low whole blood and erythrocyte levels of glutathione in hemodialysis and peritoneal dialysis patients

Dialysis patients are reported to have impaired antioxidant mechanisms, including those involving glutathione-dependent enzymes. This study used high-performance liquid chromatography assays that directly measure total (oxidized + reduced) glutathione and its precursor cysteine (CYS) to compare the whole blood of hemodialysis (prehemodialysis and posthemodialysis) and peritoneal dialysis patients to that of blood donors with no known kidney disease (n=20 in each group). The levels in erythrocytes were calculated from that data (as nmol/g hemoglobin) because these cells are the major compartment of blood glutathione and their survival may be shortened by oxidant damage. Both dialysis groups had significantly (P=0.0001) higher CYS levels in the plasma compartment than the controls (251 nmol/mL), with prehemodialysis levels (432 nmol/mL) being greater than peritoneal dialysis levels (334 nmol/mL). Hemodialysis acutely lowered CYS levels (215 nmol/mL) below those of controls. Expressed per milliliter whole blood, both dialysis groups had significantly (P=0.0001) lower glutathione levels than controls (1,276 nmol/mL), with prehemodialysis and peritoneal dialysis levels being similar (778 and 912 nmol/mL). Values increased prehemodialysis to posthemodialysis, consistent with hemoconcentration. Expressed per gram hemoglobin, the dialysis groups had significantly (P < 0.015) lower glutathione levels than the controls (8,938 nmol/g hemoglobin), with similar prehemodialysis, posthemodialysis, and peritoneal dialysis values (7,207, 7,315, and 7,915 nmol/g hemoglobin, respectively). In summary, hemodialysis and peritoneal dialysis patients are at increased risk from oxidative stress due to glutathione deficiency in whole blood and erythrocytes.

The role of the oxidative state of glutathione and glutathione-related enzymes in anemia of hemodialysis patients

OBJECTIVE

To investigate the oxidative state of glutathione and glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), and glucose-6-phosphate dehydrogenase (G-6-PD) levels in patients with chronic renal failure (CRF) and controls.

RESULTS

Erythrocyte GSH levels of patients were decreased, but GSSG was not significantly different from that of controls. Also, plasma GSH levels were not different, although GSSG was increased. GSSG/GSH ratios in erythrocyte and plasma were significantly higher in CRF patients. Erythrocyte GSSG-R activity was high, but G-6-PD and GPX were low.

CONCLUSIONS

The findings suggest that: 1. Low GSH is related to decreased G-6-PD activities. 2. The reduction of peroxides with GPX are decreased by low GSH and low GPX activity. 3. GSSG may react with hemoglobin and causes protein aggregation in erythrocytes. These alterations cause hemolysis and could play a role in the pathogenesis of anemia in hemodialyzed patients.

Chloramine removal from water used in hemodialysis

Several outbreaks of hemolysis in hemodialysis patients have occurred when chloramines in the public water supply have not been adequately removed by the dialysis unit's water purification system. Chloramines are not removed by reverse osmosis or deionization, and need to be either adsorbed by filtration through granular activated carbon (GAC) or neutralized by chemical reduction by ascorbic acid (vitamin C) added to the dialysate. Chloramine levels in the incoming water can fluctuate unpredictably, and failures of both systems have occurred when chloramines have exhausted their capacity. The medical and technical issues associated with both methods are explored in detail. Safety depends on critical care in the design of the system and rigorous testing more than once daily. Most dialysis units now depend on GAC filters, two of which should be placed in series so that chloramine breakthrough can be detected after the first one, before the second one fails. Comprehensive standards in force in California have not yet been applied universally.

Glutathione and morbidity in a community-based sample of elderly

This study examined the association of blood glutathione level, a potential marker of physiological/functional aging, with a number of biomedical/psychological traits in a subgroup (N = 33) of a representative sample of community-based elderly. Higher glutathione levels were associated with fewer number of illnesses (p < 0.05), higher levels of self-rated health (p < 0.01), lower cholesterol (p < 0.05), lower body mass index, and lower blood pressures. Subjects with diagnoses of arthritis, diabetes, or heart disease (as assessed by physicians) had at least marginally significant lower glutathione levels than those who were disease free. Glutathione, together with age and a measure of suppressed anger, accounted for 39% of the variance of an index of morbidity. Glutathione, by itself, accounted for 24% of the variance. To our knowledge, this is the first evidence of an association of higher glutathione levels with higher levels of physical health in a sample of community-based elderly. Further studies in large samples are needed to investigate glutathione as a potential overall health risk factor for morbidity among the elderly.

Reversal of selenium and zinc deficiencies in chronic hemodialysis patients by intravenous sodium selenite and zinc gluconate supplementation. Time-course of glutathione peroxidase repletion and lipid peroxidation decrease

In six chronic dialyzed uremic patients, an intravenous sodium selenite (Se 50 micrograms during 5 wk and then 100 micrograms) and zinc gluconate (Zn 5 mg) supplementation was performed during 20 wk at each dialysis session three times weekly. Before supplementation, plasma Se and Zn, plasma and erythrocytes (RBC) antioxidant metallo-enzymes glutathione peroxidase (GPX), and superoxide dismutase (SOD) were significantly decreased, whereas lipid peroxidation (as thiobarbituric acid reactants TBARs) was increased. To obtain a significative change in plasma selenium, we had to use an Se dose of 100 micrograms/dialysis session. Then, treatment-increased plasma Se (from 0.58 +/- 0.09 to 0.89 +/- 0.16 mumol/L) led to a repletion of RBC-GPX (from 29.6 +/- 6 to 43 +/- 5.8 U/g Hb) and increased plasma GPX levels (from 62 +/- 13 to 151 +/- 43 U/L). Plasma Zn and RBC-SOD did not vary significantly. The change of TBARs was not observed between wk 1 and 4. They decreased significantly between wk 4 (4.80 +/- 0.21 mumol/L) and wk 20 (4.16 +/- 0.26 mumol/L). We noted a low correlation between TBARs and plasma GPX. A strong correlation was observed between Se and plasma GPX. The reversal of Se deficiencies should reduce oxidative damage observed in these patients.

The effect of erythropoietin on the cellular defence mechanism of red blood cells in children with chronic renal failure

The glutathione redox system, haemoglobin (Hb) oxidation, the activity of antioxidant enzymes and the lipid peroxidation product malonyl dialdehyde (MDA) were studied in red blood cells (RBCs) during administration of recombinant human erythropoietin (rhEPO) over 12 weeks in ten children maintained on haemodialysis. A rapid increase in the reticulocyte count was accompanied by a slower rise in total Hb concentration. The mean level of oxidized glutathione (GSSG) increased from 13.2 +/- 5.3 nmol/g Hb to 56.7 +/- 15.8 nmol/g Hb 4 weeks after the start of rhEPO (P < 0.001), followed by a fall to the basal value. Reduced glutathione (GSH) levels showed a smaller though constant elevation during rhEPO therapy (P < 0.001). Before rhEPO treatment, incubation of RBCs for 1 h with acetylphenylhydrazine induced a decrease in GSH concentration compared with controls (P < 0.001), which became more pronounced in the first few weeks of rhEPO therapy (P < 0.001). In addition, the percentage of Hb derivatives (metHb and haemichrome) increased in the first 4 weeks of rhEPO therapy (P < 0.001). Although there was no significant difference between the values obtained preEPO and during EPO treatment, MDA levels were continuously higher and superoxide dismutase, catalase and glutathione peroxidase concentrations were lower than in the controls (P < 0.001). These results are compatible with oxidative damage to the RBCs in the early period of rhEPO therapy in children with end-stage renal failure. The GSH-GSSG system, as an important cellular defence mechanism of the RBCs, appears to be severely affected.

Erythrocyte defense mechanisms against free oxygen radicals in haemodialysed uraemic children

Changes in erythrocyte lipid peroxidation (measured as the concentration of malonyl dialdehyde), glutathione metabolism, antioxidant enzyme activities (glutathione peroxidase, catalase, and superoxide dismutase), the oxidized products of haemoglobin (Hb), and hydrogen peroxide (H2O2)-induced haemolysis were studied in six children with chronic renal failure treated with serial acetate and bicarbonate haemodialysis (HD). Ten age- and sex-matched children acted as controls. Malonyl dialdehyde levels were significantly higher and antioxidant enzyme activities lower in uraemic red blood cells (RBCs) compared with controls (P less than 0.05). Incubation of RBCs for 1 h with acetylphenylhydrazine induced a decrease in the concentration of reduced glutathione (P less than 0.001) and an increase in the level of oxidized products of Hb (P less than 0.001), but only in the uraemic patients. The H2O2 haemolysis test revealed a mild (n = 3) to increased (n = 3) haemolysis in the uraemic RBCs. Oxidative haemolysis is probably a multifactorial process in uraemic patients, and may be an important risk factor in HD therapy.

Whole blood superoxide anion generation and efficiency of some erythrocyte antioxidant systems during recombinant human erythropoietin therapy of uremic anemia

Six chronic uremic patients on regular hemodialysis treatment were given recombinant human erythropoietin (r-huEPO) in a dose of 50 U/kg of body weight intravenously thrice weekly for 14 weeks. Following r-huEPO therapy, unstimulated whole blood superoxide anion (O2) generation did not change significantly, while opsonized zymosan-stimulated whole blood O2 generation increased. At the same time, erythrocyte superoxide dismutase and, in particular, glutathione peroxidase activities were found to be reducing with concomitant lowering of erythrocyte malonyldialdehyde (MDA) concentrations and increase in plasma MDA concentrations.